Definitely agree about potential healthcare benefits of wearables for people that need constant monitoring like diabetics, too.
I have a fitbit watch for running - i thought i'd get bored of it really quickly and expected to return it, but its actually surprisingly useful. The inbuilt gps tracks my runs so I can leave my phone at home (I used to run with my phone on a belt which was annoying and bulky). It also tracks heartrate constantly which gives a more accurate estimation of calories burnt etc. That said it was quite expensive!